The costs associated with acquiring licensed bands are leading many WISPs to consider license-exempt solutions for niche markets such as rural areas, large underserved campuses and "hotspot" applications.
License-exempt spectrum, while cost effective, comes with its own set of challenges. Finding a clean spectrum to offer services becomes challenging in any license-exempt regime. Most regulatory authorities restrict power emission of license-exempt equipment making it more difficult to scale-up operations or increase signal strength to mitigate increasing RF noise. Moreover, by its very nature, there is often little or no 'coordination' between operators setting up networks in the unlicensed band. Finally, most equipment available for license-exempt use has targeted Wireless LAN type setup and is not suited for broad roll-out.
Aperto® Network's PacketMAX® product line features a number of advanced technologies, several of which were introduced to the broadband wireless access market for the first time by Aperto. These technologies span all layers of the protocol stack, from the antenna at layer 1 to application level QoS control at layer 7. PacketMAX is, therefore, best poised to tackle the challenges of license-exempt spectrum, bringing unprecedented value to the wireless operators and their subscribers.
Improving License-Exempt WiMAX with PacketMAX®
The WiMAX Forum defines the profiles that any WiMAX-compliant broadband wireless access systems must support, in order to achieve inter-operability. Aperto's PacketMAX incorporates certain technology enhancements that are over and above what WiMAX prescribes. Aperto R&D has produced breakthrough technologies such as OptimaLink dynamic link parameter control, ServiceQ quality of service and bandwidth management, and RapidBurst® transmission control that have been integrated in the new license-exempt architecture for frequency contention, interference resilience, and service quality. At the core of Aperto license-exempt solution is the adaptive TDD system architecture that increases spectral efficiency and mitigates interference. The 802.16-2004 compliant 256 FFT OFDM PHY makes an ally of multipath for greater performance in outdoor and non line-of-sight (NLOS) conditions. Operators have the confidence to design SLA-backed and tiered service offerings for enterprise and residential customers using 5.4GHz and 5.8GHz license-exempt frequency bands.
Aperto uses a number of technologies to make the wireless link more robust to multipath and interference, including:
- ARQ or Automatic Re-Transmissions
- Adaptive Coding and Modulation
- Antenna Diversity
- Dynamic Power Control
- Automatic Frequency Selection
Aperto Networks is the first WiMAX system to offer US FCC and ETSI standard Dynamic Frequency Selection (DFS). Some countries, such as UK, are considering mandatory use of DFS function to restrict interference from too many license-exempt systems affecting critical government communication networks. DFS periodically scans the airwaves to detect and avoid channels being used by radar signals. Transmission stops immediately when interference occurs, the system searches for a clear channel, and the new frequency is broadcast from the base unit to all subscriber units within the sector.
All PacketMAX systems seamlessly integrate with existing WiMAX deployments and have common management and provisioning from the powerful WaveCenter EMS Pro® console.